communities-contracts/certora/specs/CommunityERC721.spec

methods {
  function balanceOf(address) external returns (uint) envfree;
  function ownerOf(uint256 tokenId) external returns (address) envfree;
  function transferable() external returns (bool) envfree;
  function totalSupply() external returns (uint) envfree;
  function maxSupply() external returns (uint) envfree;
  function setMaxSupply(uint256 newMaxSupply) external returns (uint);
  function mintTo(address[]) external;
  function mintedCount() external returns (uint) envfree;
  function safeBatchTransferFrom(address from, address[] to, uint256[] tokenIds, bytes data) external;
  function countAddressOccurrences(address[], address) external returns (uint) envfree;
  function _.onERC721Received(address, address, uint256, bytes) external => NONDET;
}

ghost mathint sumOfBalances {
    init_state axiom sumOfBalances == 0;
}

hook Sstore _balances[KEY address addr] uint256 newValue (uint256 oldValue) {
    sumOfBalances = sumOfBalances - oldValue + newValue;
}

hook Sload uint256 balance _balances[KEY address addr] {
    require sumOfBalances >= to_mathint(balance);
}

function safeAssumptions() {
  requireInvariant mintCountGreaterEqualTotalSupplyAndTotalSupplyEqBalances();
}

invariant mintCountGreaterEqualTotalSupplyAndTotalSupplyEqBalances()
    to_mathint(mintedCount()) >= to_mathint(totalSupply()) &&
      to_mathint(totalSupply()) == sumOfBalances;

rule integrityOfMintTo {
  requireInvariant mintCountGreaterEqualTotalSupplyAndTotalSupplyEqBalances();

  address[] addresses;
  env e;

  mathint totalSupply_before = totalSupply();
  mathint maxSupply = to_mathint(maxSupply());

  address addr;

  require totalSupply_before < maxSupply;
  require totalSupply_before + addresses.length <= maxSupply;

  mathint balance_addr_before = balanceOf(addr);
  mathint count = countAddressOccurrences(addresses, addr);
  mintTo(e, addresses);

  mathint totalSupply_after = totalSupply();
  mathint balance_addr_after = balanceOf(addr);

  assert totalSupply_after == totalSupply_before + addresses.length;
  assert balance_addr_after == balance_addr_before + count;
}

rule maxSupplyCannotBeLowerThanMintedCount() {
  require maxSupply() >= mintedCount();

  env e;
  uint256 newMaxSupply;

  setMaxSupply(e, newMaxSupply);

  assert maxSupply() >= mintedCount();
}

rule maxSupplyNotLowerThanTotalSupply(env e, method f) {
  require maxSupply() >= totalSupply();
  requireInvariant mintCountGreaterEqualTotalSupplyAndTotalSupplyEqBalances();

  calldataarg args;
  f(e, args); // call all public/external functions of a contract

  assert maxSupply() >= totalSupply();
}

rule mintToReverts() {
  address[] addresses;
  env e;

  mathint supply_before = totalSupply();
  mathint max_supply = maxSupply();
  mathint minted_count = mintedCount();

  require supply_before <= max_supply;
  require minted_count >= supply_before;

  mintTo@withrevert(e, addresses);

  bool reverted = lastReverted;

  assert (supply_before + addresses.length > max_supply) => reverted;

  satisfy supply_before == max_supply && addresses.length > 0 && reverted;
}

rule mintToRelations() {
  address[] addresses_1;
  address[] addresses_2;
  env e;

  require addresses_1.length == 2;
  require addresses_1.length == addresses_2.length;

  require addresses_1[0] != addresses_1[1];
  require addresses_1[0] == addresses_2[1];
  require addresses_1[1] == addresses_2[0];

  mathint supply_before = totalSupply();
  mathint max_supply = maxSupply();
  mathint minted_count = mintedCount();

  require supply_before <= max_supply;
  require minted_count >= supply_before;

  address a;

  storage s1 = lastStorage;
  mintTo(e, addresses_1);
  mathint balance_s1 = balanceOf(a);

  mintTo(e, addresses_2) at s1;

  mathint balance_s2 = balanceOf(a);
  assert balance_s1 == balance_s2;
}

rule safeBatchTransferFromReverts() {

  address from;
  address[] to;
  uint256[] tokenIds;
  bytes data;
  env e;

  mathint supply_before = totalSupply();
  mathint max_supply = maxSupply();
  mathint minted_count = mintedCount();

  require supply_before <= max_supply;
  require minted_count >= supply_before;

  safeBatchTransferFrom@withrevert(e, from, to, tokenIds, data);

  bool reverted = lastReverted;

  assert (tokenIds.length != to.length) => reverted;
}

rule safeBatchTransferFromRelations() {
  address from;
  address[] to;
  uint256[] tokenIds;
  bytes data;
  env e;

  require to.length == tokenIds.length;

  mathint supply_before = totalSupply();
  mathint max_supply = maxSupply();
  mathint minted_count = mintedCount();

  require supply_before <= max_supply;
  require minted_count >= supply_before;

  address a;

  storage s1 = lastStorage;
  safeBatchTransferFrom(e, from, to, tokenIds, data);
  mathint balance_s1 = balanceOf(a);

  safeBatchTransferFrom(e, from, to, tokenIds, data) at s1;

  mathint balance_s2 = balanceOf(a);
  assert balance_s1 == balance_s2;
}